Activity-based costing (ABC) is a costing method that identifies activities in an organization and assigns the cost of each activity to all products and services according to the actual consumption by each. Therefore, this model assigns more indirect costs (overhead) into direct costs compared to conventional costing.

The UK's Chartered Institute of Management Accountants (CIMA), defines ABC as an approach to the costing and monitoring of activities which involves tracing resource consumption and costing final outputs. Resources are assigned to activities, and activities to cost objects based on consumption estimates. The latter utilize cost drivers to attach activity costs to outputs.

The Institute of Cost Accountants of India says, ABC systems calculate the costs of individual activities and assign costs to cost objects such as products and services on the basis of the activities undertaken to produce each product or services. It accurately identifies sources of profit and loss.

The Institute of Cost & Management Accountants of Bangladesh (ICMAB) defines activity-based costing as an accounting method which identifies the activities which a firm performs and then assigns indirect costs to cost objects.

With ABC, a company can soundly estimate the cost elements of entire products, activities and services, that may help inform a company's decision to either:

In a business organization, the ABC methodology assigns an organization's resource costs through activities to the products and services provided to its customers. ABC is generally used as a tool for understanding product and customer cost and profitability based on the production or performing processes. As such, ABC has predominantly been used to support strategic decisions such as pricing, outsourcing, identification and measurement of process improvement initiatives.

Following strong initial uptake, ABC lost ground in the 1990s compared to alternative metrics, such as Kaplan's balanced scorecard and economic value added. An independent 2008 report concluded that manually driven ABC was an inefficient use of resources: it was expensive and difficult to implement for small gains, and a poor value, and that alternative methods should be used. Other reports show the broad band covered with the ABC methodology.

However, application of an activity based recording may be applied as an addition to activity based accounting, not as a replacement of any costing model, but to transform concurrent process accounting into a more authentic approach.